Heretofore, there have been used several types of blowers having a cross flow fan in which the flow produced by the fan is changed in the flowing direction thereof. In a blower disclosed in U.S. Pat. No. 3,116,011, a vortex stabilizing plate and a back guider are rotated as an integral unit through 180.degree. about the rotating axis of a fan so that the flowing direction is reversed without changing the rotating direction of the fan itself. And in a blower according to British Pat. No. 876,614, two sets of vortex stabilizing plates and back guiders are provided symmetrically in relation to the axis of a fan. With this arrangement, the back guiders are moved alternatively to part from an outer periphery of the fan for adjusting size and shape of spaces on the suction side and delivery side so that the flowing direction is reversed. Further, in a blower of Japanese Pat. No. 44,408/1972, a vortex stabilizing plate has connected thereto on the suction side thereof a guider which is different from the vortex stabilizing plate, and the guider is rotated about the connecting portion to reverse the flowing direction.
However, in those blowers, the flow is merely reversed and there always exists only one suction port and only one delivery port. Thus, it is very difficult to divide the air sucked in in one suction port of a fan and deliver the air flows thus produced in two directions which are nearly opposite relative to each other, as is done in the present invention. Viewed from the standpoint of the dividing of an air flow, one method employs diffusers disposed in the delivery port portion to divide the flow, and in another method (U.S. Pat. No. 3,288,355), a back guider is separated into two parts so that the one part can serve as a diffuser for obtaining divided flows. The former method in which the diffusers are arranged in the delivery port is not based on a new idea and only divides the flow in the same direction. The latter method in which the back guider is separated into two parts also merely divides the flow in the nearly same directions. In this case, since the back guider is separated into two parts, the overall flow guiding effect of the two separated back guiders is naturally smaller than the flow guiding effect of the original one back guider, resulting in a decrease in the total amount of air delivered.